michelfPcfem…
Note that with a “full” load of 200,000 lbs of fuel, the KC-767AT is still ~20,000 lbs under its MTOW…
And what UK airbases could the KC-767AT not use “at MTOW” that the KC-30 could (at even a reduced TO weight for an equal fuel offload)?
And don’t give me tha BS that the KC-767AT need a 8,000′ runway. Even the Italian & Japanese KC-767s with less powerful engines need <7,700′. The 8,000′ number is just a requirement for use of NATO bases.
Well, RAF Fairford and Mildenhall come to mind…..but don’t let the real requirements of a rejected take off at MTOW deter you from believing otherwise.
The Boeing KC-767AT is 85% US/15% non-US workshare & the NG/EADS KC-30 is ~58% US/42% non-US workshare. That is a difference of 27%.
As a matter of fact 767 & 777 airframes (just the airframe) are 30% foreign manufactured. But the A330/KC-30 airframe (again, just the airframe) is 95+% foreign (non-US manufactured). But the airframe cost/workshare is only a portion of the total cost/workshare…
[I]Shame you avoided point but I mentioned total contract value.. not just airframe but all the support which was IIRC required as part of the contract…[/I]
On the contrary, one (the KC-767AT) is better for the requirements. It meets or exceeds all key requirements (something that can not be truthfully said of the KC-30), requires much less infrastructure developement to be utilized to its full potential (& provides superior capability using the existing infrastructure), has significantly lower total life-cycle costs, et cetera.
The USAF does have a requirment for two tankers, the medium KC-135 replacement tanker (KC-X & KC-Z) and the large KC-10 replacement tanker (KC-Y).
Unfortunately (for your ‘theatre tactical refuller’ and a ‘strategic refueller’ idea) there are far to many who insist that even the medium KC-135 replacement tanker (KC-X & KC-Z) have a significant airlift capability (note that for the loads that the KC-X will carry the KC-767AT exceed the airlift capability of the C-17 – quite significant for an airfrace for which airlift is a secondary role).
You have identified the issue; insistence on airlift capability that made that the prime driver of the KC-30 choice…because the USAF know damn well that getting two airframes is a very long shot and are hedging their bets…yet you failed to understand the consequnces of that.. looking at the KC767AT in that light, the KC-30 offers greater potential ot cover the KC-Y requirements by fleet expansion rather than by new airframe adoption….
I would also disagree with your view that the 767AT was ‘better’, but the matter is more sematics than real….in addition the AT airframe, contrary to your view, will demand more basic design confirmation as the mix of parts, whilst all individually proven does, by Boening’s own admission, pose interesting challenges. Nobody doubts that it can be done and done well, Boeing’s performance on the KC-767 program for both Italy and Japan does help support the view that the new version will take more time to ‘deliver’ than the KC-30. The point is now further clouded by the proposal of the 777 variant .. talk about exceeding requirements. It seems Boeing has twigged that bigger may be better and it certainly trumps the KC-30..
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michelfThe name is ‘Jordan’ actually, but you weren’t to know 😉
I just find it so frustrating that the politics is such an issue, and clouds so much of the procurement cycle; preventing discussion on which is actually the most suitable type to buy.
I’m not a fan of political games and points scoring 😡
Jordan,
Apologies…
I agree its frustrating.. but perhaps look at it in another fashion… without politics we would not have all this hard ware to admire and hence these discussions would not happen….
Its might be a high price to pay.. but one that is perhaps worth it…
michelfNeed I point out that the industrial concerns of the contract should be irrelevant to the USAF, all they need is the most suitable aircraft for their needs. Bringing in workshare concerns is a political exercise, and if that’s what the USA wants to do then fine, but then our discussion of the capabilities becomes pointless.
John,
Military procurement is political…its is only political.. the technical side is merely a sideshow..if it wasn’t for political will to do X,Y and Z that demands an armed capacity then the military and its hardware aspect is irrelevant.
So the politcal and commercial aspects are the prime drivers of these programmes and the issues that pcfem and irtusk are bashing about are the real issues, the ones the USAF do need to pay attention to.
Both proposals provide a step change in refueling capability and transport..so the USAF is a potentially a winner with either…mind you the reality that the KC767 could not use UK airbases at MTOW is a bit of an issue requiring a reduced MTOW (but still allowing far greater range and off load than the 135…)
The real issue is whether or not the creation of an all new airframe/ aircraft assembly plant in a new area of the US is desirable or not and regardless of pcfem exhortations the 767 airframe is by no means wholly manufactured in the US…but he is right that whilst the percentages may be small (its actually a 10% difference, not 27% of the declared contract value) the sheer numbers make a vast difference…saying that c. $5billion of US tax payers money is gonig overseas to Europe, percieved as mainly France is a political issue that needs to be addressed. Mind you with the recent lavish spending on Gm and other car makers perhaps the US population has become blase about these sums.
To say that one is ‘better’ than the other is completely wrong…as due to thier relative sizes and capabilities they are only comparable in very limited areas….
What would be more interesting would be to for the USAF to require a true ‘theatre tactical refuller’ and a ‘strategic refueller’, a mix that could have been delivered via a mix of the A310MRTT and KC-45… or a KC-757/777 or 747/8 mix…
The former being much more comparable to the 135 in size and range…and the later giving a serious uplift in capability…but then again perhaps they knew that getting one new tanker was ambitious enough and tried to cover the bases in a single hit.
michelfIts interesting because it seems the primary point of this report is being misseed here….
Its a Swiss report, based in the French speaking part of Switzerland. The military is traditionally held in highest esteem in the German speaking part and it is that part that derives the greatest financial benefit from the military, especially the aircraft element.
Secondly the procurement of Mirages was not exactly a ‘clean affair’ and even the purchase of the Tigers and Hornets gave rise to a doubts as to how ‘clean’ those deals were…
So there is inherent bias in the foundation of the report…with well know worries that yet another arms deal for Switzerland will be tainted by allegations….Dassault is already well know and understood to be a ‘fast and loose’ player….and whilst the Rafale may be a good technical solution it would instantly be viewed in the same light as the Mirage deal..
There was some appeal in purchasing a ‘clean’ SAAB aircraft or even the Tyhoon (even if it is far too much a/c for the actual Swiss needs) and this report sends a clear message to the Swiss viewers and readers that neither airframe is free of allegations of bribery etc etc.
The French speaking part of Switzerland traditionally is to the left of the German speaking part and has given rise to the group that proposes the disbandment of the armed forces, a notion that was taken to a national referendum.. can you imagine other nations asking the general population to vote for the disbandment of its armed forces.
So the report has, as its central theme, that arms purchases.. from pretty much whomsoever will come with a inherent ‘bribe’ in some form and this will ultimately benefit another part of Switzerland. Never mind that within the first report it is clear that Swiss based holding companies have been implicated in the bribery implicated in the deals mentionned.
This report is not an attack on BAE or SAAB or Dassault, its an overall attack on the procurement of arms by Switzerland that sees bribery as part of that deal and ‘should’ this ostensibly neutral nation be a part of that and retain its armed forces. The use of BAE and SAAB is a vehicule to demonstrate that and so whether or not its the Tornado order or the Tyhoon or whatever is actaully not relevant…..
With that in mind does the actual accuracy make much difference? We are all aware of past actions on all sides that are at best unethicla and at worse illegal. Has the game really changed that much or are the methods used more discrete and difficult to detect? One would like to think that the game has changed, but when you read of the off set deals and so forth they appear to be ways of legally providing financial incentives to purchasers…
michelfScience Museum is possibly the best option… easiest by Tube and you can easily get to Paddington and LHR from there.
BUT aviation hall is pretty dark so pics are a challenge.
IWM is great as well, but remember its half term so loads of kids about in either location.
michelfThe Belfast Truss is a structurally efficient way of spanning large distances whilst using very common (read cheap) elements.
The large number and their relatively short length means a large potential supply of basic material.
For the bow string truss each individual element is carrying a greater percentage of the load (either in tension or compression) and hence needs a higher specification.. (for which read higher quality and hence cost).
What makes them so interesting is that it was the material cost that drove this design, not the labour cost required to assemble the much larger number of elements to create each truss. In contemporary building the higher priced material which demands lower labour cost would be the one selected every time as labour is now the driving element in such construction.
The upper element is curved as it approximates best the shortest path between two individual cross brace…inagine the bow string as a greatly magnified Belfast…But the roof pitch that goes over the top of either is a choice… it could be pitched (more effective but more expensive roof) or curved… cheaper but has other performance issues to do with drainage.
The Duxford Hangers are pretty safe…especially as Duxford is now creating an ‘buildings’ based educational programme…
michelfWell the same could be said for XT867, which i believe is still on gate duty at Leuchars. Given that this example has served with i think all RN Phantom squadrons in its time i find it hard to believe that it is still not in the FAA museum.
OK so we cannot save everything, but surely those with an important history should come first..!
Not to pick on you Wyvern…but priority should be given to the ‘first’…
The FAAM have the first UK spec Phantom (YF-4K) at Yeovilton…. in the ‘Carrier Exhibition’… OK its the ‘prototype’ and never served but is that an issue?
The question is do they need more than one to represent the type? If not then the first is more important than the last or the oldest or most served, certainly in historical terms.
If more than one then yes go for one which has the most history etc etc.
michelfHad a quick look a dry weights of the engines….
If we take an average weight of each TF33 at 4,700lbs (approx) to produce 17,000lbs thrust…we have 9,400lbs weight to produce 34,000lbs of thrust.
To produce an equivalent thrust we would need a CFM56-5C series engine at approx 7,500lbs….
This is just the dry weight of the engine… but if we assume (the mother of all f##k-ups I know) that nacelle/ plyon and accessory weights are equivalents that is approx 1,800lbs less per pylon.. or 3,600lbs per side…
It would be interesting if they were to take that weight saving, to see how that would change the wing bending moment relief in the long term….
michelfCan someone explain to me how the A-10 won when the A-7D was holding most of the cards: -HUD -INS -auto-pilot -superior radar -moving map display -speed -range -battle proven -already in service -from the Texas congressional district; aside from a big honkin’ gun, which wasn’t even installed yet, durability and an extra dry pylon or two?
In cases like this it is much more enlightening to look at why the fly off took place at all….taking Loofaboy’s source as a clear version of events (always a risk I know) it is clear that this fly off had little to do with airframe abilities and roles and everything to do with political support.
The Air Force, having already invested heavily in the A-9/A-10 fly offs as well as developing the GAU-8 in a competitive prototype situation (a ‘shoot-off’), were under pressure to ‘demonstrate’ that their solution was the ‘better’ one.
So the weighting of the criteria were very carefully selected to high light the features it felt were the most important.
When this is considered the answer to the original question is pretty moot, as it does nothing to shed light on what was actaully going on.
michelfWhat sort of state is that poor B26 in????????????????
Not looking too bad compared to the state of some of the airframes he has had restored (at least the ones done over here).
Seriously there are at least two airframes illustrated in that collection that, IIRC, were done over here and the ‘in-depth’ nature of the work was astounding. They literally took years of full time work.
If we assume the B-26 will be restored along the same lines scheduling the team and space to do it as part of a much larger collection is quite a task.. literally one that takes years, especially to a collection located in FLorida which needs to deal with ‘unexpected’ restoration tasks due to the odd hurriance etc.
And lets face it he is not in a ‘hurry’ to get them done, prefering to have an exemplar restoration carried out..even if it takes longer than expected.
michelfThere are two schools of thought on this..
1) Replacement engines (so 8 out; 8 in) possibly technically the easiest but the scope in terms of savings (fuel/ maintenance etc) is more limited and so capital versus saving shows a low return.
2) Re-engineering the propulsion system. I.e replacing 8 engines with 4 engines. This involves far more in depth study of the initial design parameters (8 engines) and how the change in engines (to 4) actually affects the wing structure and so forth.
In addition there are all of the interaction issues that need far more work going from 8 to 4, from new pylons to the interaction with all the aerodynamic controls.
Unlike the KC-135 programme where the number of engines remained the same the change from 8 to 4 for the B-52 would alter a basic design parameter. Its not to say it cannot be done, merely it worth it.
michelfAnd that claim could very well have been overstated as well, which would certainly be embarassing to the designers.
Not really.
The overall structural demands on the WTC were determined by the potential wind loading being applied to the buildings by a hurriance force wind.
This was calculated at some 6000 tonnes on a single face.
Admittedly this is not a point load (which is effectively what an airliner is) at a higher speed.
michelfYou forgot one small detail. Given the situation of thin cores with very little lateral stability with the forces applied assymetrically, the building would never have collapsed in the way it did. You would have had long thin fragments of cantilever beams spreaded out in radial direction.
No why do you say that?
1) The core was built on a floor by floor module unlike the facade which was a three stroey unit…the idea that an off centre collpase (South tower) would reveal a radial pathology is therefore unlikely. The concentric collpase of the north tower would be more likely to reveal soem vertical elements. however their inherent unit size would make long thin fragments (say more than two/three floors improbable (but not impossible.)
2) Whilst the lift shafts which drove the selection of a reinforced steel core where enclosed by a ‘drywall’ (edit to clarify that in this case concrete panels) construction there were othe steel columns ‘reinforced’ by concrete within the cores. These would have collpased differentially from the others, perhaps inducing eccentric local loadings , further reducing the possiblity of long fragments.
Details matter in terms of connections used, tolerances, etc., for pure material evaluation the tests of the metal sheets are/wer appropriate.The issue is that when I used the word ‘furnace’ I meant a furance.. not teh sheet steel that goes to make one. That is the ‘detail’ which was omitted from your highly detailed, yet somewhat irrelevant figures. I suggest therefore that if a ‘steel furnace’ is such a good strucutral solution it should be more present in building structures. Steel plate is however a very good structural material…that was never in question.
Again details that matter, but seem to be missed.Feel free to bring them in, I will gladly ask them questions. Until then I hardly can take it as an argument, everyone can claim something and/or post internet based images, you surely understand…
Not sure what you mean here.
I have no doubt your knowledge of materials is greater than mine. Perhaps your knowledge of structures is as well. What I would challenge is that those who were commissioned to do the ‘pathology’ of the WTC collpase in order to inform/ educate/ enlighten us as to what design issues were revealled by the collapse were not able to use knowledge such as yours to establish what happened. As mentionned before material behaviour is not the issue, the behaviour of the structural systems is…and I would prefer to rely on those with whom I have worked to design and build the building illustrated and who did carry out the ‘autoposy’. There is no arguement. You have stated facts, which although interesting are not the issue being discussed.
You can claim tests in your lab.. so can anyone else..Excellent. Now we start finding an agreement. The last question remains, what happened to the cores?
See above. These were not monolithic strucutres, but elemental ones, hybrid to boot. Certainly the eccentric collapse of the south tower makes your hypothesis improbable.
I think I understand those more than sufficiently.
I am going to assume you do, but quoting figures, of little direct relevance, in the abstract, perhaps taken off the internet are not exactly an arguement.. are they?
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michelfIf connections between floor structure and outside walls would have been the reason for collapse, the you would have ended up with the stiff cores still sticking out into the sky. That didn’t happen.
The way the buildings vanished completely, it must have been the cores that collapsed, not the auxilliary structures. That is simple and logical.
Can you back up this ‘very poorly’ claim with something? Ever tried to apply loads on a steel furnace so that you act so self-confident?
Just asking because we in our lab have tested the performance of red-heated metal sheets as structural elements and guess what, contrary to farmer-boy beliefs their performance is nowhere near being ‘poor’… The measured Young’s modulus at roughly 700 deg was evaluated between 24 and 25 million psi, (compare to 30-31 mil psi at room temp). 25 million psi is still roughly 60% stiffer than high grade titanium at room temperature (15.5 million psi)..
Are you sure that given your knowledge you wanna continue this debate? :rolleyes: Go on, I am ready..
There is no if or but about the connection failure being the key to the collapse. The cores as unstrainted cantilevers have very little inherent lateral stability and the focres applied asymmetrically on the unrestrained cores as the surrounding floorplates collapsed caused the core to topple. Hence the total collapse.
If your beloved steel furnace (notice that you tested sheet steel, not a complete element but details don’t matter do they?) performs so well in a structural role I guess I’ll be looking to my structural engineers to propose this solution in the long span floors we are building, perhaps as the lower flange of the I sections? What do you think? An appropriate use?
Or an ineffective, inappropriate selection of both material and form to the necessary task. Perhaps your lab could tell us?
Actually don’t bother I’ll get the engineers I worked with on this (see Swiss RE image) or who are working on this (on site with another tall building in central London).. to give me the advice on the strucutral issues inherent to high rise buildings, fire etc etc…to enable my team to design out many of the fire risks and enable our fire engineers to model the proposed scheme correctly and in the light of the WCC events.
Or perhaps your point, correctly made, is that material failure was not the cause. Not it was a bolted connection detail that failed. This element, as a combination of I sections with holes drilled in the vertical flange, jointing pieces, equally drilled and bolted to the perimeter beam offers far less overall performance than the individual components.
But you’re right, given my knowledge I’ll not continue to debate…I’ll just continue to challenge you and your lab to actually understand enough about the details and behaviour of the materials needed.
michelfKerosene burns at 800-850 degrees max. Steel has high thermal conductivity, that means it can quickly distribute heat into the whole structure, effectively furthermore lowering its temperature to ca 500-600 deg in the most affected areas.
THERE IS NO weakening process in high grade steel at that temperature, be it 600 deg or even 900 deg. Even the cheapest fossil fuel heating units made of crappy metal easily work at that temperature without any damage. If you live in a house, then go to your basement and check for yourself.
Or you could read the post collapse analysis carried out by both fire and structural engineers who determined the following:
1) The impact of the aircraft was ‘successfully’ accomodated by the structure as designed.
2) The post impact fire, allied to absent (due to on going and illegal work) or deteriorated (due to poor initial installation and quality and ineffective on going maintenance and inspection) fire protection to the structural steel allowed the connections between the floor structure and external load bearing perimeter wall to fail leading to collapse of floors onto each other. This instant increase in load applied to weakend structural connections created a progressive and increasing structural collapse of the building.
In addition the nature of the external wall as a load bearing but unrestained element meant that once the ‘domino’ effect began there was no inherent ‘brake’ point in the collapse.
Or you could rely on using your domestic steel furnace (designed as a heat containing element but performs very poorly as a strucutral steel element) as an example…:rolleyes:
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